How do I reduce Mac System storage?

If your Mac is a few years old, you’ll have noticed a mysterious entity slurping up your precious storage: “System”. There is, however, a way to reduce the impact of this greedy memory hog. Here’s how to reduce Mac System storage.

Before we begin, allow me to explain the roots of this article. Over the past couple of years, I’ve noticed the grey “System” section of my aged Mac exponentially increase (check yourself by clicking on the Apple icon in the top-left of the screen, selecting “About This Mac” and then clicking the Storage tab in the window that appears). It can’t be deleted via a simple button press in macOS and there’s a notable lack of advice on the Apple website.

Days of delving around internet forums yielded no useful answers – until I finally stumbled upon a simple fix that reduced the system section by over 20GB. To be honest, it’s a bit of a brute-force solution, but, according to numerous users online, it’s the one Apple has recommended in the past.

NOTE: The problem’s probably not as bad as you think it is. One trick is to get to the Storage breakdown shown above and then wait for a few minutes. You’ll see that the System section is gradually broken down into smaller sections (such as iCloud), but chances are that a hefty chunk will still be greyed out. If so, read on…

How to reduce Mac system storage

First, you’ll have to boot your Mac into something called “Safe mode”. This is simple to do, but it’s best to wait until you’ve got a spare ten minutes as it can take a while.

Click the Apple icon in the top-left of the screen and select “Restart…”. When everything starts to disappear from your desktop, hold down Shift and don’t release it until you see a white Apple logo and progress bar on a black background.

We’d hazard a guess that you’ve never done this before. If so, the progress bar will take significantly longer (think three to five minutes) to load that with a normal restart.

Once that’s done, you’ll see the icon below in the top-right of the login screen.

Now comes the slightly strange bit: immediately restart your Mac normally. Once that’s done, and if you’re in luck, heading to About This Mac | Storage will show that the System section has been massively reduced.

But how? Apple is tight-lipped about what actually makes up System, but the consensus online is that it’s full of caches (data that’s stored so it can be served more quickly). Booting in Safe mode will hopefully get rid of some of this gunk, reducing the impact on your storage.

We repeat: hopefully. If you’ve tried the method above with, or without, success, please let me know in the comments below. In the meantime, I’ll carry on searching for a workable way to reduce Mac System storage even further – preferably without third-party software.

Speaking of which, there are dozens of forum and YouTube “experts” who claim that using such-and-such software – or, even worse, deleting files willy-nilly – can solve the problem. Always take these posts/videos with a shovel of salt as the consequences can be severe. For instance, Dr Cleaner, an app that’s frequently recommended on Mac forums, was found to be harvesting users’ browser histories last September.